Method for uplink transmission in wireless communication system, and device therefor

ABSTRACT

According to one embodiment of the present invention, a method by which a terminal configured to have two or more processing times transmits a hybrid automatic repeat request-acknowledgment (HARQ-ACK) in a wireless communication system comprises the steps of: receiving, from a base station, a downlink control channel for indicating a downlink data channel, and the downlink data channel in one or more downlink subframes; and transmitting, to the base station, HARQ-ACK information on the downlink data channel in an uplink subframe corresponding to the one or more downlink subframes, wherein the HARQ-ACK information transmitted in the uplink subframe includes HARQ-ACK information on a downlink data channel in accordance with only one processing time among the two or more processing times, and cannot include HARQ-ACK information on a downlink data channel in accordance with the rest processing times.

CLAIM OF PRIORITY

This application is a U.S. National Patent Application and claimspriority to International Application Serial No. PCT/KR2017/008434,filed on Aug. 4, 2017, which claims the benefit of U.S. ProvisionalApplication No. 62/377,659, filed on Aug. 21, 2016, 62/401,839, filed onSep. 29, 2016, 62/406,381, filed on Oct. 10, 2016, 62/417,317, filed onNov. 3, 2016, 62/421,176, filed on Nov. 11, 2016 and 62/479,245, filedon Mar. 30, 2017, which are all hereby incorporated by reference hereinin their entirety.p

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method for uplink transmission and a devicetherefor.

BACKGROUND ART

Latency of packet data is one of the important performance metrics.Providing faster access to the Internet for the end users may be one ofthe important challenges not only to LTE but also to the design of anext-generation mobile communication system, which is called new RAT.

The present invention deals with uplink transmission such as HARQfeedback or uplink data transmission in a wireless communication systemsupporting reduction of latency.

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies inan uplink transmission method for reducing latency.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

The object of the present invention can be achieved by providing amethod for transmitting hybrid automatic repeat request-acknowledgment(HARQ-ACK) in a wireless communication system, the method beingperformed by a terminal configured to have two or more processing times,the method including receiving, from a base station, a downlink controlchannel indicating a downlink data channel and the downlink data channelin one or more downlink subframes, and transmitting, to the basestation, HARQ-ACK information about the downlink data channel in anuplink subframe corresponding to the one or more downlink subframe,wherein the HARQ-ACK information transmitted in the uplink subframeincludes HARQ-ACK information about a downlink data channel according toonly one processing time of the two or more processing times and doesnot include HARQ-ACK information about a downlink data channel accordingto the other processing times.

Additionally or alternatively, a minimum interval between the uplinksubframe and the one or more downlink subframes corresponding to theuplink subframe may be three or fewer subframes.

Additionally or alternatively, when the number of the one or moredownlink subframes corresponding to the uplink subframe is greater thanor equal to a predetermined value, the HARQ-ACK information about thedownlink data channel may be bundled.

Additionally or alternatively, when the number of the downlink subframescorresponding to the uplink subframe is greater than or equal to apredetermined value, the HARQ-ACK information about the downlink datachannel may be transmitted through a specific physical uplink controlchannel (PUCCH) format.

Additionally or alternatively, an information set indicating the one ormore downlink subframes corresponding to the uplink subframe may beconfigured for each of the processing times.

Additionally or alternatively, the information set may be determinedaccording to HARQ-ACK load balancing or latency priority.

In another aspect of the present invention, provided herein is aterminal configured to transmit hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) in a wireless communication system,the terminal including a transmitter and a receiver, and a processorconfigured to control the transmitter and the receiver, wherein theterminal is configured to have two or more processing times, wherein theprocessor is configured to receive, from a base station, a downlinkcontrol channel indicating a downlink data channel and the downlink datachannel in one or more downlink subframes, and transmit, to the basestation, HARQ-ACK information about the downlink data channel in anuplink subframe corresponding to the one or more downlink subframe, andwherein the HARQ-ACK information transmitted in the uplink subframeincludes HARQ-ACK information about a downlink data channel according toonly one processing time of the two or more processing times and doesnot include HARQ-ACK information about a downlink data channel accordingto the other processing times.

Additionally or alternatively, a minimum interval between the uplinksubframe and the one or more downlink subframes corresponding to theuplink subframe may be three or fewer subframes.

Additionally or alternatively, when the number of the one or moredownlink subframes corresponding to the uplink subframe is greater thanor equal to a predetermined value, the HARQ-ACK information about thedownlink data channel may be bundled.

Additionally or alternatively, when the number of the downlink subframescorresponding to the uplink subframe is greater than or equal to apredetermined value, the HARQ-ACK information about the downlink datachannel may be transmitted through a specific physical uplink controlchannel (PUCCH) format.

Additionally or alternatively, an information set indicating the one ormore downlink subframes corresponding to the uplink subframe may beconfigured for each of the processing times.

Additionally or alternatively, the information set may be determinedaccording to HARQ-ACK load balancing or latency priority.

In another aspect of the present invention, provided herein is a methodfor transmitting uplink data in a wireless communication system, themethod being performed by a terminal and including receiving a downlinkcontrol channel including an uplink grant from a base station in adownlink subframe, and transmitting, to the base station, uplink dataindicated by the uplink grant in an uplink subframe corresponding to thedownlink subframe, wherein, when the terminal is configured to have ashortened processing time, a minimum interval between the downlinksubframe and the uplink subframe is three or fewer subframes.

Additionally or alternatively, when a second uplink grant having aprocessing time longer than the shortened processing time correspondingto the uplink subframe is received, uplink data indicated by the seconduplink grant may not be transmitted.

Additionally or alternatively, an interval between the downlink subframeand the uplink subframe may be determined according to an index value inthe uplink grant.

The above technical solutions are merely some parts of the embodimentsof the present invention and various embodiments into which thetechnical features of the present invention are incorporated can bederived and understood by persons skilled in the art from the followingdetailed description of the present invention.

Advantageous Effects

According to embodiments of the present invention, uplink transmissionmay be efficiently performed.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the present invention, and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

FIG. 1 illustrates an exemplary radio frame structure in a wirelesscommunication system.

FIG. 2 illustrates an exemplary downlink/uplink (DL/UL) slot structurein the wireless communication system.

FIG. 3 illustrates an exemplary DL subframe structure in a 3GPPLTE/LTE-A system.

FIG. 4 illustrates an exemplary UL subframe structure in the 3GPPLTE/LTE-A system.

FIG. 5 illustrates conflict of PUCCH resources linked to PDCCHs receivedin different DL subframes in a TDD system.

FIGS. 6 and 7 illustrate an example of PUSCH transmission according to aUL grant in the TDD system.

FIGS. 8, 9, and 10 illustrate PUCCH resources for DL HARQ based on aresource offset according to a subframe type and/or a processing time.

FIG. 11 illustrates operation of a UE according to an embodiment of thepresent invention.

FIG. 12 is a block diagram of devices for implementing the embodiment(s)of the present invention.

BEST MODE

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The accompanying drawings illustrate exemplary embodiments ofthe present invention and provide a more detailed description of thepresent invention. However, the scope of the present invention shouldnot be limited thereto.

In some cases, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

In the present invention, a user equipment (UE) is fixed or mobile. TheUE is a device that transmits and receives user data and/or controlinformation by communicating with a base station (BS). The term ‘UE’ maybe replaced with ‘terminal equipment’, ‘Mobile Station (MS)’, ‘MobileTerminal (MT)’, ‘User Terminal (UT)’, ‘Subscriber Station (SS)’,‘wireless device’, ‘Personal Digital Assistant (PDA)’, ‘wireless modem’,‘handheld device’, etc. A BS is typically a fixed station thatcommunicates with a UE and/or another BS. The BS exchanges data andcontrol information with a UE and another BS. The term ‘BS’ may bereplaced with ‘Advanced Base Station (ABS)’, ‘Node B’, ‘evolved-Node B(eNB)’, ‘Base Transceiver System (BTS)’, ‘Access Point (AP)’,‘Processing Server (PS)’, etc. In the following description, BS iscommonly called eNB.

In the present invention, a node refers to a fixed point capable oftransmitting/receiving a radio signal to/from a UE by communication withthe UE. Various eNBs can be used as nodes. For example, a node can be aBS, NB, eNB, pico-cell eNB (PeNB), home eNB (HeNB), relay, repeater,etc. Furthermore, a node may not be an eNB. For example, a node can be aradio remote head (RRH) or a radio remote unit (RRU). The RRH and RRUhave power levels lower than that of the eNB. Since the RRH or RRU(referred to as RRH/RRU hereinafter) is connected to an eNB through adedicated line such as an optical cable in general, cooperativecommunication according to RRH/RRU and eNB can be smoothly performedcompared to cooperative communication according to eNBs connectedthrough a wireless link. At least one antenna is installed per node. Anantenna may refer to an antenna port, a virtual antenna or an antennagroup. A node may also be called a point. Unlink a conventionalcentralized antenna system (CAS) (i.e., single node system) in whichantennas are concentrated in an eNB and controlled an eNB controller,plural nodes are spaced apart at a predetermined distance or longer in amulti-node system. The plural nodes can be managed by one or more eNBsor eNB controllers that control operations of the nodes or schedule datato be transmitted/received through the nodes. Each node may be connectedto an eNB or eNB controller managing the corresponding node via a cableor a dedicated line. In the multi-node system, the same cell identity(ID) or different cell IDs may be used for signal transmission/receptionthrough plural nodes. When plural nodes have the same cell ID, each ofthe plural nodes operates as an antenna group of a cell. If nodes havedifferent cell IDs in the multi-node system, the multi-node system canbe regarded as a multi-cell (e.g., macro-cell/femto-cell/pico-cell)system. When multiple cells respectively configured by plural nodes areoverlaid according to coverage, a network configured by multiple cellsis called a multi-tier network. The cell ID of the RRH/RRU may beidentical to or different from the cell ID of an eNB. When the RRH/RRUand eNB use different cell IDs, both the RRH/RRU and eNB operate asindependent eNBs.

In a multi-node system according to the present invention, which will bedescribed below, one or more eNBs or eNB controllers connected tomultiple nodes may control the nodes such that signals aresimultaneously transmitted to or received from a UE through some or allnodes. While there is a difference between multi-node systems accordingto the nature of each node and implementation form of each node,multi-node systems are discriminated from single node systems (e.g., acentralized antenna system (CAS), conventional MIMO systems,conventional relay systems, conventional repeater systems, etc.) since aplurality of nodes provides communication services to a UE in apredetermined time-frequency resource. Accordingly, embodiments of thepresent invention with respect to a method of performing coordinateddata transmission using some or all nodes may be applied to varioustypes of multi-node systems. For example, a node refers to an antennagroup spaced apart from another node by a predetermined distance ormore, in general. However, embodiments of the present invention, whichwill be described below, may even be applied to a case in which a noderefers to an arbitrary antenna group irrespective of node interval. Inthe case of an eNB including an X-pole (cross-polarized) antenna, forexample, the embodiments of the preset invention are applicable on theassumption that the eNB controls a node composed of an H-pole antennaand a node composed of a V-pole antenna.

A communication scheme through which signals are transmitted/receivedvia plural transmit (Tx)/receive (Rx) nodes, signals aretransmitted/received via at least one node selected from plural Tx/Rxnodes, or a node transmitting a downlink signal is discriminated from anode transmitting an uplink signal is called multi-eNB MIMO or CoMP(Coordinated Multi-Point Tx/Rx). Coordinated transmission schemes fromamong CoMP communication schemes can be categorized into JP (JointProcessing) and scheduling coordination. The former may be divided intoJT (Joint Transmission)/JR (Joint Reception) and DPS (Dynamic PointSelection) and the latter may be divided into CS (CoordinatedScheduling) and CB (Coordinated Beamforming). DPS may be called DCS(Dynamic Cell Selection). When JP is performed, more variouscommunication environments can be generated, compared to other CoMPschemes. JT refers to a communication scheme by which plural nodestransmit the same stream to a UE and JR refers to a communication schemeby which plural nodes receive the same stream from the UE. The UE/eNBcombine signals received from the plural nodes to restore the stream. Inthe case of JT/JR, signal transmission reliability can be improvedaccording to transmit diversity since the same stream is transmittedfrom/to plural nodes. DPS refers to a communication scheme by which asignal is transmitted/received through a node selected from plural nodesaccording to a specific rule. In the case of DPS, signal transmissionreliability can be improved because a node having a good channel statebetween the node and a UE is selected as a communication node.

In the present invention, a cell refers to a specific geographical areain which one or more nodes provide communication services. Accordingly,communication with a specific cell may mean communication with an eNB ora node providing communication services to the specific cell. Adownlink/uplink signal of a specific cell refers to a downlink/uplinksignal from/to an eNB or a node providing communication services to thespecific cell. A cell providing uplink/downlink communication servicesto a UE is called a serving cell. Furthermore, channel status/quality ofa specific cell refers to channel status/quality of a channel or acommunication link generated between an eNB or a node providingcommunication services to the specific cell and a UE. In 3GPP LTE-Asystems, a UE can measure downlink channel state from a specific nodeusing one or more CSI-RSs (Channel State Information Reference Signals)transmitted through antenna port(s) of the specific node on a CSI-RSresource allocated to the specific node. In general, neighboring nodestransmit CSI-RS resources on orthogonal CSI-RS resources. When CSI-RSresources are orthogonal, this means that the CSI-RS resources havedifferent subframe configurations and/or CSI-RS sequences which specifysubframes to which CSI-RSs are allocated according to CSI-RS resourceconfigurations, subframe offsets and transmission periods, etc. whichspecify symbols and subcarriers carrying the CSI RSs.

In the present invention, PDCCH (Physical Downlink ControlChannel)/PCFICH (Physical Control Format Indicator Channel)/PHICH(Physical Hybrid automatic repeat request Indicator Channel)/PDSCH(Physical Downlink Shared Channel) refer to a set of time-frequencyresources or resource elements respectively carrying DCI (DownlinkControl Information)/CFI (Control Format Indicator)/downlink ACK/NACK(Acknowledgement/Negative ACK)/downlink data. In addition, PUCCH(Physical Uplink Control Channel)/PUSCH (Physical Uplink SharedChannel)/PRACH (Physical Random Access Channel) refer to sets oftime-frequency resources or resource elements respectively carrying UCI(Uplink Control Information)/uplink data/random access signals. In thepresent invention, a time-frequency resource or a resource element (RE),which is allocated to or belongs toPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH, is referred to as aPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE orPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource. In the followingdescription, transmission of PUCCH/PUSCH/PRACH by a UE is equivalent totransmission of uplink control information/uplink data/random accesssignal through or on PUCCH/PUSCH/PRACH. Furthermore, transmission ofPDCCH/PCFICH/PHICH/PDSCH by an eNB is equivalent to transmission ofdownlink data/control information through or onPDCCH/PCFICH/PHICH/PDSCH.

FIG. 1 illustrates an exemplary radio frame structure used in a wirelesscommunication system. FIG. 1(a) illustrates a frame structure forfrequency division duplex (FDD) used in 3GPP LTE/LTE-A and FIG. 1(b)illustrates a frame structure for time division duplex (TDD) used in3GPP LTE/LTE-A.

Referring to FIG. 1, a radio frame used in 3GPP LTE/LTE-A has a lengthof 10 ms (307200 Ts) and includes 10 subframes in equal size. The 10subframes in the radio frame may be numbered. Here, Ts denotes samplingtime and is represented as Ts=1/(2048*15 kHz). Each subframe has alength of 1 ms and includes two slots. 20 slots in the radio frame canbe sequentially numbered from 0 to 19. Each slot has a length of 0.5 ms.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources can be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame can be configured differently according to duplex mode.Downlink transmission is discriminated from uplink transmission byfrequency in FDD mode, and thus the radio frame includes only one of adownlink subframe and an uplink subframe in a specific frequency band.In TDD mode, downlink transmission is discriminated from uplinktransmission by time, and thus the radio frame includes both a downlinksubframe and an uplink subframe in a specific frequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink- to-Uplink Switch- DL-UL point Subframe numberconfiguration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  D S U U UD D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D D D D 6 5ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes threefields of DwPTS (Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS(Uplink Pilot TimeSlot). DwPTS is a period reserved for downlinktransmission and UpPTS is a period reserved for uplink transmission.Table 2 shows special subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special Normal cyclic Extended Normal Extendedsubframe prefix in cyclic prefix cyclic prefix cyclic prefixconfiguration DwPTS uplink in uplink DwPTS in uplink in uplink 0  6592 ·T_(s) 2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s)1 19760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — —

FIG. 2 illustrates an exemplary downlink/uplink slot structure in awireless communication system. Particularly, FIG. 2 illustrates aresource grid structure in 3GPP LTE/LTE-A. A resource grid is presentper antenna port.

Referring to FIG. 2, a slot includes a plurality of OFDM (OrthogonalFrequency Division Multiplexing) symbols in the time domain and aplurality of resource blocks (RBs) in the frequency domain. An OFDMsymbol may refer to a symbol period. A signal transmitted in each slotmay be represented by a resource grid composed of N_(RB) ^(DL/UL)*N_(sc)^(RB) subcarriers and N_(symb) ^(DL/UL) OFDM symbols. Here, N_(RB) ^(DL)denotes the number of RBs in a downlink slot and N_(RB) ^(UL) denotesthe number of RBs in an uplink slot. N_(RB) ^(DL) and N_(RB) ^(UL)respectively depend on a DL transmission bandwidth and a UL transmissionbandwidth. N_(symb) ^(DL) denotes the number of OFDM symbols in thedownlink slot and N_(symb) ^(UL) denotes the number of OFDM symbols inthe uplink slot. In addition, N_(sc) ^(RB) denotes the number ofsubcarriers constructing one RB.

An OFDM symbol may be called an SC-FDM (Single Carrier FrequencyDivision Multiplexing) symbol according to multiple access scheme. Thenumber of OFDM symbols included in a slot may depend on a channelbandwidth and the length of a cyclic prefix (CP). For example, a slotincludes 7 OFDM symbols in the case of normal CP and 6 OFDM symbols inthe case of extended CP. While FIG. 2 illustrates a subframe in which aslot includes 7 OFDM symbols for convenience, embodiments of the presentinvention can be equally applied to subframes having different numbersof OFDM symbols. Referring to FIG. 2, each OFDM symbol includes N_(RB)^(DL/UL)*N_(sc) ^(RB) subcarriers in the frequency domain. Subcarriertypes can be classified into a data subcarrier for data transmission, areference signal subcarrier for reference signal transmission, and nullsubcarriers for a guard band and a direct current (DC) component. Thenull subcarrier for a DC component is a subcarrier remaining unused andis mapped to a carrier frequency (f0) during OFDM signal generation orfrequency up-conversion. The carrier frequency is also called a centerfrequency.

An RB is defined by N_(symb) ^(DL/UL) (e.g., 7) consecutive OFDM symbolsin the time domain and N_(sc) ^(RB) (e.g., 12) consecutive subcarriersin the frequency domain. For reference, a resource composed by an OFDMsymbol and a subcarrier is called a resource element (RE) or a tone.Accordingly, an RB is composed of N_(symb) ^(DL/UL)*N_(sc) ^(RB) REs.Each RE in a resource grid can be uniquely defined by an index pair (k,l) in a slot. Here, k is an index in the range of 0 to N_(symb)^(DL/UL)*N_(sc) ^(RB)−1 in the frequency domain and l is an index in therange of 0 to N_(symb) ^(DL/UL)−1.

Two RBs that occupy N_(sc) ^(RB) consecutive subcarriers in a subframeand respectively disposed in two slots of the subframe are called aphysical resource block (PRB) pair. Two RBs constituting a PRB pair havethe same PRB number (or PRB index). A virtual resource block (VRB) is alogical resource allocation unit for resource allocation. The VRB hasthe same size as that of the PRB. The VRB may be divided into alocalized VRB and a distributed VRB depending on a mapping scheme of VRBinto PRB. The localized VRBs are mapped into the PRBs, whereby VRBnumber (VRB index) corresponds to PRB number. That is, nPRB=nVRB isobtained. Numbers are given to the localized VRBs from 0 to N_(VRB)^(DL)−1, and N_(VRB) ^(DL)=N_(RB) ^(DL) is obtained. Accordingly,according to the localized mapping scheme, the VRBs having the same VRBnumber are mapped into the PRBs having the same PRB number at the firstslot and the second slot. On the other hand, the distributed VRBs aremapped into the PRBs through interleaving. Accordingly, the VRBs havingthe same VRB number may be mapped into the PRBs having different PRBnumbers at the first slot and the second slot. Two PRBs, which arerespectively located at two slots of the subframe and have the same VRBnumber, will be referred to as a pair of VRBs.

FIG. 3 illustrates a downlink (DL) subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 3, a DL subframe is divided into a control region anda data region. A maximum of three (four) OFDM symbols located in a frontportion of a first slot within a subframe correspond to the controlregion to which a control channel is allocated. A resource regionavailable for PDCCH transmission in the DL subframe is referred to as aPDCCH region hereinafter. The remaining OFDM symbols correspond to thedata region to which a physical downlink shared chancel (PDSCH) isallocated. A resource region available for PDSCH transmission in the DLsubframe is referred to as a PDSCH region hereinafter. Examples ofdownlink control channels used in 3GPP LTE include a physical controlformat indicator channel (PCFICH), a physical downlink control channel(PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc. ThePCFICH is transmitted at a first OFDM symbol of a subframe and carriesinformation regarding the number of OFDM symbols used for transmissionof control channels within the subframe. The PHICH is a response ofuplink transmission and carries an HARQ acknowledgment (ACK)/negativeacknowledgment (NACK) signal.

Control information carried on the PDCCH is called downlink controlinformation (DCI). The DCI contains resource allocation information andcontrol information for a UE or a UE group. For example, the DCIincludes a transport format and resource allocation information of adownlink shared channel (DL-SCH), a transport format and resourceallocation information of an uplink shared channel (UL-SCH), paginginformation of a paging channel (PCH), system information on the DL-SCH,information about resource allocation of an upper layer control messagesuch as a random access response transmitted on the PDSCH, a transmitcontrol command set with respect to individual UEs in a UE group, atransmit power control command, information on activation of a voiceover IP (VoIP), downlink assignment index (DAI), etc. The transportformat and resource allocation information of the DL-SCH are also calledDL scheduling information or a DL grant and the transport format andresource allocation information of the UL-SCH are also called ULscheduling information or a UL grant. The size and purpose of DCIcarried on a PDCCH depend on DCI format and the size thereof may bevaried according to coding rate. Various formats, for example, formats 0and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3 and 3Afor downlink, have been defined in 3GPP LTE. Control information such asa hopping flag, information on RB allocation, modulation coding scheme(MCS), redundancy version (RV), new data indicator (NDI), information ontransmit power control (TPC), cyclic shift demodulation reference signal(DMRS), UL index, channel quality information (CQI) request, DLassignment index, HARQ process number, transmitted precoding matrixindicator (TPMI), precoding matrix indicator (PMI), etc. is selected andcombined based on DCI format and transmitted to a UE as DCI.

In general, a DCI format for a UE depends on transmission mode (TM) setfor the UE. In other words, only a DCI format corresponding to aspecific TM can be used for a UE configured in the specific TM.

A PDCCH is transmitted on an aggregation of one or several consecutivecontrol channel elements (CCEs). The CCE is a logical allocation unitused to provide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). For example, a CCE corresponds to 9 REGs and an REG correspondsto 4 REs. 3GPP LTE defines a CCE set in which a PDCCH can be located foreach UE. A CCE set from which a UE can detect a PDCCH thereof is calleda PDCCH search space, simply, search space. An individual resourcethrough which the PDCCH can be transmitted within the search space iscalled a PDCCH candidate. A set of PDCCH candidates to be monitored bythe UE is defined as the search space. In 3GPP LTE/LTE-A, search spacesfor DCI formats may have different sizes and include a dedicated searchspace and a common search space. The dedicated search space is aUE-specific search space and is configured for each UE. The commonsearch space is configured for a plurality of UEs. Aggregation levelsdefining the search space is as follows.

TABLE 3 Search Space S_(k) ^((L)) Aggregation Number of PDCCH Type LevelL UE-specific 1 6 6 2 12 6 4 8 2 8 16 2 Common 4 16 4 8 16 2

A PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to CCEaggregation level. An eNB transmits a PDCCH (DCI) on an arbitrary PDCCHcandidate with in a search space and a UE monitors the search space todetect the PDCCH (DCI). Here, monitoring refers to attempting to decodeeach PDCCH in the corresponding search space according to all monitoredDCI formats. The UE can detect the PDCCH thereof by monitoring pluralPDCCHs. Since the UE does not know the position in which the PDCCHthereof is transmitted, the UE attempts to decode all PDCCHs of thecorresponding DCI format for each subframe until a PDCCH having the IDthereof is detected. This process is called blind detection (or blinddecoding (BD)).

The eNB can transmit data for a UE or a UE group through the dataregion. Data transmitted through the data region may be called userdata. For transmission of the user data, a physical downlink sharedchannel (PDSCH) may be allocated to the data region. A paging channel(PCH) and downlink-shared channel (DL-SCH) are transmitted through thePDSCH. The UE can read data transmitted through the PDSCH by decodingcontrol information transmitted through a PDCCH. Informationrepresenting a UE or a UE group to which data on the PDSCH istransmitted, how the UE or UE group receives and decodes the PDSCH data,etc. is included in the PDCCH and transmitted. For example, if aspecific PDCCH is CRC (cyclic redundancy check)-masked having radionetwork temporary identify (RNTI) of “A” and information about datatransmitted using a radio resource (e.g., frequency position) of “B” andtransmission format information (e.g., transport block size, modulationscheme, coding information, etc.) of “C” is transmitted through aspecific DL subframe, the UE monitors PDCCHs using RNTI information anda UE having the RNTI of “A” detects a PDCCH and receives a PDSCHindicated by “B” and “C” using information about the PDCCH.

A reference signal (RS) to be compared with a data signal is necessaryfor the UE to demodulate a signal received from the eNB. A referencesignal refers to a predetermined signal having a specific waveform,which is transmitted from the eNB to the UE or from the UE to the eNBand known to both the eNB and UE. The reference signal is also called apilot. Reference signals are categorized into a cell-specific RS sharedby all UEs in a cell and a modulation RS (DM RS) dedicated for aspecific UE. A DM RS transmitted by the eNB for demodulation of downlinkdata for a specific UE is called a UE-specific RS. Both or one of DM RSand CRS may be transmitted on downlink. When only the DM RS istransmitted without CRS, an RS for channel measurement needs to beadditionally provided because the DM RS transmitted using the sameprecoder as used for data can be used for demodulation only. Forexample, in 3GPP LTE(-A), CSI-RS corresponding to an additional RS formeasurement is transmitted to the UE such that the UE can measurechannel state information. CSI-RS is transmitted in each transmissionperiod corresponding to a plurality of subframes based on the fact thatchannel state variation with time is not large, unlike CRS transmittedper subframe.

FIG. 4 illustrates an exemplary uplink subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 4, a UL subframe can be divided into a control regionand a data region in the frequency domain. One or more PUCCHs (physicaluplink control channels) can be allocated to the control region to carryuplink control information (UCI). One or more PUSCHs (Physical uplinkshared channels) may be allocated to the data region of the UL subframeto carry user data.

In the UL subframe, subcarriers spaced apart from a DC subcarrier areused as the control region. In other words, subcarriers corresponding toboth ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a component remaining unused forsignal transmission and is mapped to the carrier frequency f0 duringfrequency up-conversion. A PUCCH for a UE is allocated to an RB pairbelonging to resources operating at a carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots.Assignment of the PUCCH in this manner is represented as frequencyhopping of an RB pair allocated to the PUCCH at a slot boundary. Whenfrequency hopping is not applied, the RB pair occupies the samesubcarrier.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response signal to a downlink data        packet on a PDSCH and indicates whether the downlink data packet        has been successfully received. A 1-bit ACK/NACK signal is        transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords. HARQ-ACK responses include positive ACK        (ACK), negative ACK (NACK), discontinuous transmission (DTX) and        NACK/DTX. Here, the term HARQ-ACK is used interchangeably with        the term HARQ ACK/NACK and ACK/NACK.    -   Channel State Indicator (CSI): This is feedback information        about a downlink channel. Feedback information regarding MIMO        includes a rank indicator (RI) and a precoding matrix indicator        (PMI).

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a soundingreference signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports various formats according toinformation transmitted thereon.

Table 4 shows the mapping relationship between PUCCH formats and UCI inLTE/LTE-A.

TABLE 4 Number of bits per PUCCH Modulation subframe, format schemeM_(bit) Usage Etc. 1 N/A N/A(exist SR (Scheduling or absent) Request) 1aBPSK 1 ACK/NACK or One SR + ACK/NACK codeword 1b QPSK 2 ACK/NACK or TwoSR + ACK/NACK codeword 2 QPSK 20 CQI/PMI/RI Joint coding ACK/NACK(extended CP) 2a QPSK + BPSK 21 CQI/PMI/RI + Normal CP ACK/NACK only 2bQPSK + QPSK 22 CQI/PMI/RI + Normal CP ACK/NACK only 3 QPSK 48 ACK/NACKor SR + ACK/NACK or CQI/PMI/RI + ACK/NACK

Referring to Table 4, PUCCH formats 1/1a/1b are used to transmitACK/NACK information, PUCCH format 2/2a/2b are used to carry CSI such asCQI/PMI/RI and PUCCH format 3 is used to transmit ACK/NACK information.

Reference Signal (RS)

When a packet is transmitted in a wireless communication system, signaldistortion may occur during transmission since the packet is transmittedthrough a radio channel. To correctly receive a distorted signal at areceiver, the distorted signal needs to be corrected using channelinformation. To detect channel information, a signal known to both atransmitter and the receiver is transmitted and channel information isdetected with a degree of distortion of the signal when the signal isreceived through a channel. This signal is called a pilot signal or areference signal.

When data is transmitted/received using multiple antennas, the receivercan receive a correct signal only when the receiver is aware of achannel state between each transmit antenna and each receive antenna.Accordingly, a reference signal needs to be provided per transmitantenna, more specifically, per antenna port.

Reference signals can be classified into an uplink reference signal anda downlink reference signal. In LTE, the uplink reference signalincludes:

i) a demodulation reference signal (DMRS) for channel estimation forcoherent demodulation of information transmitted through a PUSCH and aPUCCH; and

ii) a sounding reference signal (SRS) used for an eNB to measure uplinkchannel quality at a frequency of a different network.

The downlink reference signal includes:

i) a cell-specific reference signal (CRS) shared by all UEs in a cell;

ii) a UE-specific reference signal for a specific UE only;

iii) a DMRS transmitted for coherent demodulation when a PDSCH istransmitted;

iv) a channel state information reference signal (CSI-RS) for deliveringchannel state information (CSI) when a downlink DMRS is transmitted;

v) a multimedia broadcast single frequency network (MBSFN) referencesignal transmitted for coherent demodulation of a signal transmitted inMBSFN mode; and

vi) a positioning reference signal used to estimate geographic positioninformation of a UE.

Reference signals can be classified into a reference signal for channelinformation acquisition and a reference signal for data demodulation.The former needs to be transmitted in a wide band as it is used for a UEto acquire channel information on downlink transmission and received bya UE even if the UE does not receive downlink data in a specificsubframe. This reference signal is used even in a handover situation.The latter is transmitted along with a corresponding resource by an eNBwhen the eNB transmits a downlink signal and is used for a UE todemodulate data through channel measurement. This reference signal needsto be transmitted in a region in which data is transmitted.

Latency of packet data is one of the important performance metrics.Providing faster access to the Internet for the end users may be one ofthe important challenges not only to LTE but also to the design of anext-generation mobile communication system, which is called new RAT.

Recent standards of LTE have introduced several technologies such ascarrier aggregation, and massive MIMO, higher modulation order in aneffort to increase the data rate. However, reducing the processing timeto improve the transmission control protocol (TCP) throughput whiledrastically reducing the latency of the user plane may be one of the keytechnologies. Recently, in the LTE standard, a method to reduce timingbetween DL reception and UL transmission of “UL grant-to-PUSCH” and “DLdata-to-DL HARQ-ACK feedback” to reduce the processing time is underdiscussion.

The present invention proposes a scheme for performing HARQ-ACK feedbackin a situation where reduction of the processing time is supported. Theinvention or the proposal disclosed herein is described based on LTE forsimplicity, but the description is also applicable to other technologiessuch as new RAT in which a different waveform/frame structure is used.Although a specific TTI length is assumed in the embodiments of thepresent invention for simplicity, the present invention is alsoapplicable to a different TTI length configuration (e.g., short TTI(sTTI) (<1 msec), longTTI (=1 msec), longerTTI (>1 msec)). For example,the sTTI may be introduced in the next-generation system in a manner inwhich the subcarrier spacing is increased. Here, the sTTI refers to aTTI that is shorter than the legacy TTI of 1 ms.

[Proposal 1] TDD UL Transmission Timing According to a ShortenedProcessing Time

According to the current LTE Rel.-13 standard, after initialtransmission of a PDCCH/PDSCH, the UE may receive the PDCCH/PDSCH andperform a procedure of detection and decoding (including blinddecoding). Thereafter, the UE may perform a coding procedure for PUCCHor PUSCH transmission in order to transmit HARQ-ACK for the PDSCH, andperform the transmission by advancing the transmission timing for timingadjustment (TA). In the FDD system, the above-described procedures(hereinafter referred to as a processing time) are performed for 3 msecbased on a normal TTI (i.e., a TTI consisting of 14 symbols), andtherefore HARQ-ACK for the PDSCH transmitted in SF #n may be transmittedon the PUCCH or PUSCH in SF #n+4.

A UE supporting the shortened processing time may require a shorter timefor the operation described above. Therefore, the HARQ-ACK for the PDSCHscheduled by a DL grant in subframe #n may be transmitted in subframe#n+k (where k is an integer less than 4).

However, in the TDD system, the DL subframe position and the UL subframeposition (and the position of a special subframe composed of DwPTS,UpPTS and a guard period) are predefined according to the TDD DL-ULconfigurations of Table 1. Even in terms of the normal TTI, the timingat which the HARQ-ACK for a PDSCH is transmitted after the PDSCH istransmitted, or the timing at which a PUSCH is transmitted after thecorresponding PDCCH for the UL grant is transmitted may not be based on4 msec anymore, but may be assigned a greater value according to the TDDDL-UL configuration. Table 5 shows timing of DL HARQ-ACK transmission ofthe UE for the PDSCH in the TDD system defined in the LTE standard. Forexample, when the TDD DL-UL configuration is set to 2, the UE transmits,in subframe #n=2, HARQ-ACK for the PDSCHs received in subframes #n−8,#n−7, #n−4, and #n−6. Here, subframes #n−8, #n−7, #n−4, and #n−6 arereferred to as a “DL association set” for the DL HARQ-ACK.

TABLE 5 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6— 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7,4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4,7 — — — — — — 5 — — 13, 12, 9, 8, 7, — — — — — — — 5, 4, 11, 6 6 — — 7 75 — — 7 7 —

When the shortened processing time is supported, the earliest time atwhich HARQ-ACK for a specific PDSCH (e.g., a PDSCH transmitted insubframe #n) can be transmitted may be advanced (to, for example,subframe #n+2 or #n+3) compared to the conventional cases, and thustiming different from the conventional DL HARQ-ACK transmission timingmay be defined. Accordingly, a new HARQ-ACK transmission scheme for thedefined timing needs to be defined.

The transmission timing of the DL HARQ-ACK for the PDSCH received by theUE may be set differently according to a processing time that ispredetermined or indicated through a higher layer/physical layer signal.Herein, the processing time may be construed as DL-to-UL Tx timing(e.g., timing at which HARQ-ACK is transmitted after the correspondingPDCCH/PDSCH transmission, timing at which an sPUSCH is transmitted aftera corresponding UL grant), and/or UL-to-DL Tx timing (e.g., timing atwhich ACK or retransmission information is transmitted after acorresponding PUSCH is transmitted, timing at which the PDCCH istransmitted after the PUCCH transmission).

Referring to FIG. 5, even if UE#0 operated by the legacy processingtiming (e.g., 4 subframes) and UE#1 supporting shortened processingtiming (e.g., 3 subframes) receive PDSCH scheduling by a DL grant indifferent subframes, there is a risk of conflict between PUCCH resourcesof the two UEs if the HARQ-ACK transmission timings for thecorresponding DL grants overlap each other and indicate the same PUCCHresource (i.e., the two PDCCHs including the DL grant have the samelowest CCE index).

In order to prevent such PUCCH resource conflict, a DL association setfor DL HARQ-ACK that is to be transmitted in a specific subframe under aspecific TDD DL-UL configuration may be configured or defineddifferently by the processing time.

In the case where a DL association set determined by the legacyprocessing time and a DL association set determined by the shortenedprocessing time are configured independently and differently for DLHARQ-ACK to be transmitted in a specific subframe under a specific TDDDL-UL configuration, a rule may be defined such that HARQ-ACK for thesubframe(s) corresponding to the intersection of the sets conforms to alegacy PUCCH resource set, while HARQ-ACK for the subframe(s) which doesnot correspond to the intersection of the sets but are in the DLassociation set determined by the shortened processing time conforms toa separate PUCCH resource set. Here, the PUCCH resource set refers to aset consisting of PUCCH resources corresponding to all (E)CCEs in the DLassociation set.

Specifically, when the earliest timing at which the HARQ-ACK for aspecific PDSCH can be transmitted in the TDD system is predetermined orconfigured through a higher/physical layer signal as subframe #n+3, theDL HARQ-ACK timing may be newly defined as shown in the following table.

TABLE 6 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 — — —3 3 — — — 3 3 1 — — 6, 3 3 — — — 6, 3 3 — 2 — — 7, 4, 6, 3 — — — — 7, 4,6, 3 — — 3 — — 7, 6, 5 5, 4 4, 3 — — — — — 4 — — 8, 7, 11, 6 6, 5, 4, 3— — — — — — 5 — — 12, 9, 8, 7, 5, — — — — — — — 4, 11, 6, 3 6 — — 6 4 4— — 6 3 —

For example, when the TDD DL-UL configuration 2 is established, the UEmay transmit, in subframe #n=2, HARQ-ACK for the PDSCHs received insubframes #n−7, #n−4, #n−6, and #n−3. Subframe #n−3, which is a subframewithin the shortened processing time and does not correspond to theintersection of a DL association set (e.g., subframes #n−8, #n−7, #n−4,and #n−6) determined by the legacy processing time and a DL associationset (e.g., subframe #n−7, #n−4, #n−6, and #n−3) determined by theshortened processing time, conforms to a separate PUCCH resource setdifferent from the PUCCH resource set determined by the DL associationset determined by the legacy processing time.

Specifically, in the TDD system, when the earliest timing at which theHARQ-ACK for a specific PDSCH can be transmitted is predetermined orconfigured through a higher/physical layer signal as subframe #n+2, theDL HARQ-ACK timing may be newly defined as shown in the following table.

TABLE 7 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 — — 22 — — — 2 2 — 1 — — 3, 2 2 — — — 3, 2 2 — 2 — — 4, 6, 3, 2 — — — — 4, 6,3, 2 — — 3 — — 7, 6, 5 5, 4 4, 3 — — — — — 4 — — 8, 7, 5, 6 5, 4, 3, 2 —— — — — — 5 — — 9, 8, 7, 5, 4, — — — — — — — 11, 6, 3, 2 6 — — 3 3 3 — —2 2 —

For example, when the TDD DL-UL configuration 2 is established, the UEmay transmit, in subframe #n=2, HARQ-ACK for the PDSCHs received insubframes #n−4, #n−6, #n−3, and #n−2. Subframe #n−2, which is a subframewithin the shortened processing time and does not correspond to theintersection of a DL association set (e.g., subframes #n−8, #n−7, #n−4,and #n−6) determined by the legacy processing time and a DL associationset (e.g., subframe #n−4, #n−6, #n−3, and #n−2) determined by theshortened processing time, conforms to a separate PUCCH resource setdifferent from the PUCCH resource set determined by the DL associationset determined by the legacy processing time.

When the shortened processing time is supported, the earliest time atwhich a PUSCH is to be transmitted after a corresponding PDCCH for aspecific UL grant (e.g., the PDCCH transmitted in subframe #n) istransmitted may be advanced (to, for example, subframe #n+2 or #n+3)compared to the conventional cases, and therefore timing different fromthe legacy PUSCH transmission timing may be defined. Accordingly, a newPUSCH transmission scheme for the defined timing needs to be defined.

The PUSCH transmission timing of a UE for UL grant in the TDD systemdefined in the LTE standard is shown in the following table. In the caseof TDD DL-UL configuration 0, the PUSCH transmission timing for a ULgrant received in subframe #n is defined as subframe #n+k and/orsubframe #n+7 according to a UL index value in the UL grant.

TABLE 8 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 4 6 46 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 — — 4 6 7 7 7 7 5

The PUSCH transmission timing for a UL grant received by the UE at aspecific point in time under a specific TDD DL-UL configuration may bepredetermined or may be defined differently according to the processingtime indicated through a higher layer/physical layer signal.

Specifically, when the earliest timing at which a PUSCH scheduled by aUL grant received at a specific time in the TDD system can betransmitted is predetermined or configured through a higherlayer/physical layer signal as subframe #n+3, the PUSCH transmissiontiming may be newly defined as shown in the following table.

TABLE 9 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 3 3 33 1 3 3 3 3 2 3 3 3 3 3 3 4 3 3 5 3 6 4 6 3 6 4

Specifically, when the earliest timing at which a PUSCH scheduled by aUL grant received at a specific time in the TDD system can betransmitted is predetermined or configured through a higherlayer/physical layer signal as subframe #n+2, the PUSCH transmissiontiming may be newly defined as shown in one of the following tables.

TABLE 10 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 2 3 23 1 2 2 2 2 2 2 2 3 3 3 3 4 2 2 5 2 6 3 3 2 2 3

TABLE 11 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 3 2 32 1 2 2 2 2 2 2 3 3 3 3 4 2 2 5 2 6 3 3 2 2 3

A rule may be defined such that PUSCH transmission timing determined bya UL index in a UL grant received by the UE at a specific time under TDDDL-UL configuration 0 is predetermined/predefined or is set to a value(different from the conventional value) indicated through a higherlayer/physical layer signal.

Specifically, the PUSCH transmission timing for UL grant received insubframe #n may be defined as subframe #n+k1 and/or subframe #n+k2according to the UL index value in the UL grant, where k1 may bedetermined by the earliest timing at which a PUSCH scheduled by the ULgrant received at a specific time (which is predetermined/predefined ordetermined according to the processing time indicated through a higherlayer/physical layer signal) can be transmitted, and k2, which is lessthan the conventional value of 7, may be determined or set differentlyaccording to the value of n (or set to a constant regardless of thevalue of n).

For example, when the rule above is applied, k1=3, k2=4 for n=0 and 5and k2=6 for n=1 and 6, the PUSCH transmission scheduled by the UL grantreceived at a specific time may be defined as shown in FIG. 6.

As another example, when the rule above is applied, k1=2 and k2=3, thePUSCH transmission timing scheduled by UL grant received at a specifictime may be defined as shown in FIG. 7.

When the transmission timing of the PUSCH for a UL grant received by theUE at a specific time under a specific TDD DL-UL configuration ispredetermined or set differently according to the processing timeindicated through a higher layer/physical layer signal, the PUSCHtransmission timings for a plurality of UL grants received at differenttimes may overlap each other. In this case, the UE may assume that theentire corresponding PUSCH scheduling is invalid, or assume that thePUSCH scheduling for a specific UL grant is valid. Specifically, in theabove-described case, an overriding operation may be defined, in whichthe UE considers the PUSCH scheduling for a UL grant having a shorterPUSCH transmission timing of the UE for the UL grant to be valid andignores the PUSCH scheduling for a UL grant having a longer PUSCHtransmission timing.

Even in the FDD system, when the transmission timing of the PUSCH for aUL grant received by the UE at a specific time is predetermined or setdifferently according to the processing time indicated through a higherlayer/physical layer signal, the PUSCH transmission timings for aplurality of UL grants received at different times may overlap eachother. For example, when DL-to-UL Tx timing for a UL grant received insubframe #n is set to 4 ms, DL-to-UL Tx timing for a UL grant receivedin subframe #n+1 is set to 3 ms, the PUSCH transmission timings for thetwo UL grants may overlap as subframe #n+4. In this case, the UE mayassume that the entire PUSCH scheduling is invalid, or assume that thePUSCH scheduling for a specific UL grant is valid. Specifically, in theabove-described case, an overriding operation may be defined, in whichthe UE considers the PUSCH scheduling for a UL grant having a shorterPUSCH transmission timing of the UE for the UL grant to be valid andignores the PUSCH scheduling for a UL grant having a longer PUSCHtransmission timing.

Further, for a UE for which enhanced interference mitigation & trafficadaptation (eIMTA) is configured, the TDD DL-UL configuration on systeminformation block 1 (SIB1) may be different from the TDD DL-ULconfiguration indicated by the reconfiguration DCI. In order toeliminate ambiguity of DL HARQ timing, eimta-HARQ-ReferenceConfig-r12may be configured, and thus the DL HARQ timing and the PUCCH resourcemay be configured to be different from each other. The following tableshows a legacy eIMTA DL association set according to the LTE standard.

TABLE 12 Higher layer parameter Higher layer ‘eimta-HARQ- parameterSubframe n ReferenceConfig-r12’ ‘subframeAssignment’ 0 1 2 3 4 5 6 7 8 92 0 — — 7, 8, 4 — — — — 7, 8, 4 — — 1 — — 8, 4 — — — — 8, 4 — — 6 — — 6,8, 4 — — — — 8, 6, 4 — — 4 0 — — 12, 7, 11, 8 7, 4, 5, 6 — — — — — — 1 —— 12, 8, 11 7, 5, 6 — — — — — — 3 — — 12, 8 4, 7 — — — — — — 6 — — 12,11, 8 4, 5, 6 — — — — — — 5 0 — — 12, 7, 11, 13, 8, 4, 9, 5 — — — — — —— 1 — — 13, 12, 8, 11, 4, 9, 5 — — — — — — — 2 — — 13, 12, 9, 11, 5 — —— — — — — 3 — — 13, 12, 5, 4, 8, 9 — — — — — — — 4 — — 13, 5, 4, 6, 9 —— — — — — — 6 — — 13, 12, 11, 6, 8, 4, 9, 5 — — — — — — —

Therefore, for a UE for which eIMTA is configured, a DL association setfor DL HARQ-ACK to be transmitted in a specific subframe under aspecific TDD DL-UL configuration may be configured or defineddifferently by the processing time. Specifically, in the TDD system,when the earliest timing at which HARQ-ACK for a specific PDSCH can betransmitted is predetermined or configured through a higherlayer/physical layer signal as subframe #n+3, the eIMTA DL associationset may be newly defined as shown in the following table.

TABLE 13 Higher layer parameter Higher layer ‘eimta-HARQ- parameterSubframe n ReferenceConfig-r12’ ‘subframeAssignment’ 0 1 2 3 4 5 6 7 8 92 0 — — 7, 6, 3, 4 — — — — 7, 6, 3, 4 — — 1 — — 7, 4 — — — — 7, 4 — — 6— — 7, 3, 4 — — — — 7, 3, 4 — — 4 0 — — 7, 6, 11, 8 4, 6, 5 — — — — — 1— — 8, 7, 11 4, 6, 5 — — — — — — 3 — — 11, 8 6, 3 — — — — — — 6 — — 7,11, 8 3, 6, 5 — — — — — — 5 0 — — 12, 7, 6, 11, 3, 8, 4, 5, 9 — — — — —— — 1 — — 12, 8, 7, 11, 4, 5, 9 — — — — — — — 2 — — 12, 9, 8, 11, 5 — —— — — — — 3 — — 12, 4, 3, 11, 8, 9 — — — — — — — 4 — — 12, 5, 4, 3, 9 —— — — — — — 6 — — 12, 7, 3, 11, 8, 4, 5, 9 — — — — — — —

Specifically, in the TDD system, when the earliest timing at whichHARQ-ACK for a specific PDSCH can be transmitted is predetermined or setthrough a higher layer/physical layer signal as subframe #n+3, the eIMTADL association set may be newly defined as shown in the following table.

TABLE 14 Higher layer parameter Higher layer ‘eimta-HARQ- parameterSubframe n ReferenceConfig-r12’ ‘subframeAssignment’ 0 1 2 3 4 5 6 7 8 92 0 — — 6, 3, 4 — — — — 6, 3, 4 — — 1 — — 6, 4 — — — — 6, 4 — — 6 — — 2,6, 4 — — — — 6, 3, 4 — — 4 0 — — 7, 6, 8, 5 3, 4, 5 — — — — — — 1 — — 8,7, 6, 5 4, 3, 5 — — — — — — 3 — — 8 3, 2 — — — — — — 6 — — 7, 6, 8, 5 4,2, 5 — — — — — — 5 0 — — 7, 6, 11, 3, 8, 4, 9, 5 — — — — — — — 1 — — 8,7, 6, 11, 4, 9, 5 — — — — — — — 2 — — 9, 8, 7, 11, 5 — — — — — — — 3 — —4, 3, 2, 11, 8, 9 — — — — — — — 4 — — 4, 3, 2, 11, 9 — — — — — — — 6 — —7, 2, 6, 11, 8, 4, 9, 5 — — — — — — —

Alternatively, a UE having received configuration of a shortenedprocessing time does not expect an eIMTA configuration for all cells.Alternatively, a UE having received an eIMTA configuration even for anyone cell may not expect a shortened processing time-relatedconfiguration for any cells. More specifically, a UE having receivedconfiguration of a shortened processing time for a specific cell doesnot expect an eIMTA configuration for any cell in the frequency band towhich the cell belongs. Alternatively, a UE having received an eIMTAconfiguration for a specific cell in a specific frequency band does notexpect a shortened processing time-related configuration for thespecific cell.

As the processing times are diversified, PDCCHs/PDSCHs (or short PDCCHs(sPDCCHs)/short PDSCHs (sPDSCHs), which refer to PDCCHs/PDSCHs accordingto an sTTI) transmitted in different subframes or TTIs may transmitHARQ-ACK in the same SF or TTI. In this case, the PUCCH resourceconflict may occur. In addition, the PUCCH resource conflict may morefrequently occur for a UE for which an eIMTA configuration is possible.In order to address this issue, the following schemes may be consideredas PUCCH resource allocation methods for an eIMTA UE which may receiveconfigurations of the legacy processing time and the shortenedprocessing time. For simplicity, for example, a Type 1 subframeindicates a fixed subframe in which the non-eIMAT UE and the eIMTA UEhave the same DL HARQ timing, a Type 2 subframe indicates a fixedsubframe in which the non-eIMTA UE and the eIMTA UE have different DLHARQ timings, and a Type 3 subframe indicates a flexible subframe. Here,the fixed subframe refers to a subframe whose usage according to the TDDDL-UL configuration is fixed to D, U, or S and is not changeable. Theflexible subframe refers to a subframe whose usage is changeableaccording to the TDD DL-UL configuration.

-   -   Alt 1: According to the current standard, in order to separate        the PUCCH resources of Type 1 and Type 2/3 subframes, a rule may        be defined such that a higher-layer-signaled offset is set and        the PUCCH resources of the Type 2/3 subframes are selected based        thereon. A rule may be defined such that the PUCCH resources of        the DL HARQ for the Type 1 and Type 2/3 subframes corresponding        to the shortened processing time are selected based on separate        resource offsets configured for each of the resources as shown        in FIG. 8. The resource offsets may be configured for separation        from PUCCH resources of DL HARQ for Type 1 and Type 2/3        subframes corresponding to the legacy processing times.        Specifically, the resource offset may be configured through a        higher layer signal, or a resource offset configured through a        higher layer signal may be finally indicated through DCI.        Alternatively, a PUCCH resource may be determined by a        combination of a resource offset configured through a higher        layer signal or the DCI and a PDCCH transmission position (e.g.,        a CCE index and/or a frequency resource (PRB index)).    -   Alt 2-1: For PUCCH resources for a part of subframes of a        specific type, a rule may be defined such that the same PUCCH        resource is shared by the legacy processing time and the        shortened processing time. Specifically, the subframes of the        specific type may be Type 1 subframes. In the case of Type 2/3        subframes, a rule may be defined such that a resource is        selected based on resource offsets configured for each of the        subframes. The resource offset may be configured through a        higher layer signal, or a resource offset configured through a        higher layer signal may be finally indicated through DCI.        Alternatively, a PUCCH resource may be determined by a        combination of the resource offset configured through a higher        layer signal or DCI and a PDCCH transmission position (e.g., a        CCE index and/or a frequency resource (PRB index)).

For example, when TDD DL-UL configuration 2 is established as shown inFIG. 9, the PUCCH resources of subframes #n−7, #n−4, and #n−6corresponding to the intersection of a DL association set (e.g.,subframes #n−8, #n−7, #n−4, and #n−6) determined by the legacyprocessing time and a DL association set (e.g., subframes #n−7, #n−4,#n−6, and #n−3) determined by the shortened processing time may beshared in subframe #n=2. As a PUCCH resource for subframe #n−3, aseparate resource may be selected as described above. In the case ofType 2/3 subframes, a resource may be selected based on the resourceoffsets configured for the respective subframes to which the legacyprocessing time and the shortened processing time are applied.

-   -   Alt 2-2: As a more general method for Alt 2-1, a rule may be        defined such that, for PUCCH resources for some of subframes of        the same type, the same PUCCH resource is shared between the        legacy processing time and the shortened processing time. For        example, as shown in FIG. 10, the PUCCH resources of the Type 1        subframes corresponding to the intersection of a DL association        set determined by the legacy processing time and a DL        association set determined by the shortened processing time may        be shared. Similarly, the PUCCH resources of the Type 2/3        subframes corresponding to the intersection of the DL        association set determined by the legacy processing time and the        DL association set determined by the shortened processing time        may also be shared. With this method, it is not necessary to        assign a separate resource offset even when the shortened        processing time is configured.

In the case where the shortened processing time is supported, DL HARQsfor PDSCHs transmitted in a large number of DL subframes may beconcentrated in one UL subframe. When PUCCH resources for an excessivelylarge number of DL HARQs need to be reserved, the efficiency of resourceutilization may be lowered. Therefore, a rule may be defined such that,when the number of DL subframes constituting a DL association set forone UL subframe is greater than or equal to a certain number (which ispredetermined/predefined or signaled through a higher/physical layersignal), HARQ-ACK (spatial) bundling is applied.

Specifically, a rule may be defined such that the rule described aboveis applied only to UEs for which a shortened processing time is set. Inaddition, a rule may be defined such that the rule described above isapplied only when the number of DL subframes constituting a DLassociation set for a specific UL subframe is greater than the number ofDL subframes constituting a DL association set determined by the legacyprocessing time.

Alternatively, a rule may be defined such that, when the number of DLsubframes constituting a DL association set for one UL subframe isgreater than or equal to a certain number (that ispredetermined/predefined or signaled through a higher/physical layersignal), DL HARQ is transmitted in PUCCH format 3/4/5 or a new PUCCHformat that supports a larger payload.

Specifically, a rule may be defined such that the rule described aboveis applied only to UEs for which a shortened processing time isconfigured. In addition, a rule may be defined such that the ruledescribed above is applied only when the number of DL subframesconstituting a DL association set for a specific UL subframe is greaterthan the number of DL subframes constituting a DL association setdetermined by the legacy processing time. In the case where PUCCHresources for PUCCH formats 3/4/5 and/or a new PUCCH format are notpredetermined/preconfigured, the rule described above may not be appliedand a rule may be defined such that the DL HARQ transmission timingdetermined by the legacy processing is applied or the HARQ-ACK (spatial)bundling is applied.

In the TDD system, a downlink assignment index (DAI) may be included ina PDCCH to count and indicate the number of PDSCHs to be transmitted onthe ACK/NACK resources of one UL subframe. For example, when one ULsubframe corresponds to three DL subframes, PDSCHs to be transmittedduring the interval of the three DL subframes may be sequentiallyassigned indexes (i.e., sequentially counted) and sent on a PDCCH forscheduling the PDSCHs, and the UE may determine whether the previousPDCCH has been correctly received based on the DAI information in thePDCCH.

There may be a plurality of processing times for a specific UE.Hereinafter, a first processing time, which is timing irrelevant to theshortened processing time configuration, may refer to a time intervalbetween the reception or a configuration related to HARQ feedback or ULtransmission through which DL HARQ feedback or UL data is transmitted inSF or TTI #n+4 when DL data or a UL grant is transmitted in SF or TTI #nand a transmission in FDD. In TDD, the first processing time, which istiming irrelevant to the shortened processing time configuration, may beat least 4 ms and may be a little longer than this value depending onthe actual DL/UL subframe. A second processing time may be timing newlyintroduced according to the shortened processing time configuration. Forexample, in FDD, the second processing time may refer to a time intervalbetween the reception or a configuration related to DL HARQ feedback orUL transmission through which DL HARQ feedback or UL data is transmittedin SF or TTI #n+3 when DL HARQ feedback or UL data is transmitted in SFor TTI #n according to transmission of DL data or a UL grant in SF orTTI #n and a transmission. In TDD, the second processing time may be atleast 3 ms and may be longer than this value depending on the actualDL/UL SF. For a single cell, the first processing time may be used in afallback operation (e.g., PDSCH/PUSCH scheduling through common searchspace (CSS) DCI and/or PDSCH scheduling through DCI format 1A or use ofgeneral RNTI), and the second processing time may be used when theshortened processing time is applied (e.g., PDSCH/PUSCH schedulingthrough UE-specific search space (USS) DCI and/or PDSCH schedulingthrough TM-dependent DCI or use of a third RNTI). In addition, in acarrier aggregation situation or dual connectivity situation, the secondprocessing time may be used when the configuration of the shortenedprocessing time operation varies among the cells. Alternatively, thesecond processing time may be used when different processing times areconfigured for a plurality of TTIs having different lengths.

For a UE for which a plurality of processing times are configured asdescribed above, the same understanding of the DAI indication scheme maybe required between the eNB and the UE. When a plurality of processingtimes are configured for the UE, a DAI transmission scheme is proposedas follows.

-   -   Alt 1: A rule may be defined such that the number of DL        subframes or TTIs in which the PDSCH is scheduled with respect        to a specific UL subframe or UL TTI in which DL HARQ is        transmitted and the number of DL grants indicating DL SPS        release do not exceed M, which is the number of elements of the        DL association set.

For example, when TDD DL-UL configuration 2 is established and the firstprocessing time is applied, the UE may transmit, in subframe #n=2,HARQ-ACKs for the PDSCHs received in subframes #n−8, #n−7, #n−4, and#n−6. On the other hand, when the second processing time is applied, theUE may transmit, in subframe #n=2, HARQ-ACKs for the PDSCHs received insubframes #n−7, #n−4, #n−6, and #n−3. Accordingly, M is defined as 4 insubframe #n=2.

In the case where subframes #n−8, #n−7, and #n−6 are scheduled by a DLgrant to which the first processing time is applied (or which isperforming the fallback operation), subframes #n−4 and #n−3 scheduled bya DL grant to which the second processing time is applied (or which isperforming a shortened processing operation), M may be 5 in subframe#n=2. If the value of M is not allowed through scheduling, the UE doesnot expect such scheduling.

-   -   Alt 2: When subframes are scheduled by a DL grant to which the        first processing time (or the second processing time) is applied        in a subframe or TTI which is one of the elements of a DL        association set determined by the first processing time (or the        second processing time) with respect to a specific UL subframe        or UL TTI in which DL HARQ is transmitted, a rule may be defined        not to allow scheduling by a DL grant to which the second        processing time (or the first processing time) is applied in        another subframe or TTI that is one of the elements of another        DL association set determined by the second processing time (or        the first processing time).

Specifically, scheduling by the DL grant to which the second processingtime (or the first processing time) is applied may not be allowed in aDL subframe or DL TTI that does not correspond to the intersection ofthe DL association set determined by the first processing time and theDL association set determined by the second processing time. Forexample, when TDD UL/DL configuration 2 is established and scheduling isperformed by a DL grant to which the first processing time is applied insubframe #n−8, scheduling by a DL grant to which the second processingtime is applied is not allowed in subframe #n−3.

A DL association set for a DL HARQ-ACK that is to be transmitted in aspecific subframe under a specific TDD DL-UL configuration may bedifferently configured or defined by the processing time. Specifically,the DL association set may be defined such that DL HARQ is distributedto the respective UL subframes as equally as possible (hereinafterreferred to as HARQ-ACK load balancing) or a delay corresponding to DLgrant-to-DL HARQ-ACK transmission is minimized (hereinafter referred toas latency priority). For example, in the TDD system, when the earliesttiming at which the HARQ-ACK for a specific PDSCH received in subframe#n can be transmitted is predetermined or configured through a higherlayer/physical layer signal as subframe #n+3, an example of the HARQ-ACKload balancing for the DL HARQ-ACK timing is shown in Table 6, and anexample of the latency priority for the DL HARQ-ACK timing is shown inthe table below.

TABLE 15 DL-UL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 — — —3 3 — — — 3 3 1 — — 6, 3 3 — — — 6, 3 3 — 2 — — 7, 6, 4, 3 — — — — 7, 4,6, 3 — — 3 — — 7, 6, 5, 4, 3 3 3 — — — — — 4 — — 11, 8, 7, 6, 5, 4, 3 3— — — — — — 5 — — 12, 11, 9, 8, 7, 6, 5, 4, 3 — — — — — — — 6 — — 6, 3 33 — — — 3 —

Specifically, for a UE for which a shortened processing time isconfigured, a rule may be defined such that whether to configure a DLassociation set using one of the HARQ-ACK load balancing and/or thelatency priority and/or explicit indication of the HARQ-ACK timing isconfigured through a higher layer/physical layer signal.

In addition, when the number of DL subframes constituting a DLassociation set for one UL subframe is greater than or equal to acertain number (which is predetermined/predefined or signaled through ahigher/physical layer signal) (particularly, when the number of DLsubframes is greater than the number of DL subframes constituting a DLassociation set determined by the legacy processing time), specificmethods for HARQ-ACK transmission are proposed below.

Alt 1: A rule may be defined such that the UE performs bundlingaccording to each processing time after performing spatial bundling foreach DL subframe.

Alt 2: A rule may be defined such that the UE performs bundlingaccording to each codeword for HARQ-ACK for one UL subframe regardlessof the processing time.

Alt 3: A rule may be defined such that the UE performs HARQ-ACKmultiplexing regardless of the processing time.

Alt 4: The UE may perform HARQ-ACK transmission using a channelselection method after performing bundling according to each processingtime. Alternatively, the UE may transmit HARQ-ACK using the channelselection method after performing spatial bundling for each DL subframe.

For example, in configuring a state of channel selection, HARQ-ACKinformation about a DL subframe corresponding to the DL association setdefined by the legacy processing time may be mapped first, and thenHARQ-ACK information about DL subframes that do not correspond to theintersection of two sets among the DL subframes corresponding to the DLassociation set defined by the shortened processing time may besequentially mapped. Alternatively, HARQ-ACK information about DLsubframes corresponding to the DL association set defined by theshortened processing time may be mapped first, and then HARQ-ACKinformation about DL subframes that do not correspond to theintersection of the two sets among the DL subframes corresponding to theDL association set defined by the legacy processing time may besequentially mapped. Additionally, a separate DAI may be defined foreach processing time.

Alt 5: HARQ-ACK transmission may be performed in PUCCH format 3/4/5 (ora new PUCCH format supporting a larger payload).

Here, a rule may be defined such that the HARQ-ACK information about aPDSCH scheduled by the shortened processing time is mapped first (or theHARQ-ACK information about a PDSCH scheduled by the legacy processingtime is mapped first). Alternatively, the HARQ-ACK information may bemapped in a predefined order regardless of the processing time. Forexample, HARQ-ACK information about a DL subframe corresponding to theDL association set defined by the legacy processing time may be mappedfirst, and then HARQ-ACK information about DL subframes that do notcorrespond to the intersection of the two sets among the DL subframescorresponding to the DL association set defined by the shortenedprocessing time may be sequentially mapped. Alternatively, HARQ-ACKinformation about DL subframes corresponding to the DL association setdefined by the shortened processing time may be mapped first, and thenHARQ-ACK information about DL subframes that do not correspond to theintersection of the two sets among the DL subframes corresponding to theDL association set defined by the legacy processing time may besequentially mapped. Additionally, a separate DAI may be defined foreach processing time.

A plurality of numerologies and/or TTI lengths and/or processing timesmay be configured for a specific UE. For example, in FDD, a firstprocessing time, which is timing irrelevant to the shortened processingtime configuration, may refer to a time interval between the receptionor a configuration related to HARQ feedback or UL transmission throughwhich DL HARQ feedback or UL data is transmitted in SF or TTI #n+4according to reception (transmission) of DL data or a UL grant in SF orTTI #n and a transmission. In TDD, the first processing time may be atleast 4 ms and may be a little longer than this value depending on theactual DL/UL subframe. A second processing time may be timing newlyintroduced according to the shortened processing time configuration.Alternatively, in a CA/DC situation, the numerology and/or TTI lengthand/or processing time may be configured differently for each cell.

In a situation where scheduling is performed with a plurality ofnumerologies and/or TTI lengths and/or processing times, a rule may bedefined such that a DAI is assigned regardless of the numerologiesand/or TTI lengths and/or processing times. Alternatively, a rule may bedefined such that DAIS are independently assigned according to therespective numerologies and/or TTI lengths and/or processing times.Alternatively, DAIS may be independently assigned to the 1 ms TTI andthe short TTI. For example, the PUSCH/PUCCH for the 1 ms TTI and thesPUSCH/sPUCCH for the 2-symbol TTI may be assigned separate DAIS,respectively.

Here, a rule may be defined such that DAIS are sequentially assigned ina transmission order of DL data channels (e.g., PDSCHs). Thetransmission times of DL data channels may be the same or overlap eachother due to different numerologies and/or TTI lengths and/or processingtimes. In this case, the DAIS may be assigned by a predefined priority.Specifically, a rule may be defined such that the DAIS are sequentiallyassigned in the order of times at which DL grants are transmitted.Alternatively, a rule may be defined such that a DAI is assigned to a DLgrant or DL data channel corresponding to a specific numerology and/orTTI length and/or processing time first.

Alternatively, a rule may be defined such that the DAIs are sequentiallyassigned in order of transmissions of DL assignment DCI.

Alternatively, a rule may be defined such that the DAIs are sequentiallyassigned in descending order of start positions of the DL allocationDCIs or the DL data channels (e.g., PDSCHs).

Alternatively, a rule may be defined such that DAIs are sequentiallyassigned in order of HARQ-ACK transmission timings. Specifically, thedefinition may be applied to a case where different TTI lengths aregiven.

As mentioned above, when subframes are scheduled by a DL grant to whichthe first processing time (or the second processing time) is applied ina subframe or TTI which is one of the elements of the DL association setdetermined by the first processing time (or the second processing time)with respect to a specific UL subframe or TTI in which DL HARQ-ACK istransmitted, a rule may be defined not to allow scheduling by a DL grantto which the second processing time (or the first processing time) isapplied in another subframe or TTI that is one of the elements ofanother DL association set determined by the second processing time (orthe first processing time).

More specifically, a rule may be defined such that a UE having receivedDL assignments (or DL grants) of different processing times that causeHARQ-ACK to be transmitted in a specific UL subframe excludes ACK/NACKfeedback information for DL data corresponding to an element of a DLassociation set determined by a longer processing time and/or configureHARQ-ACK feedback including ACK/NACK feedback information about DL datacorresponding to an element of a DL association set determined by ashorter processing time. This operation may be to prioritize schedulingfor the shorter processing time. Specifically, the excluded/includedACK/NACK feedback information may be ACK/NACK feedback information abouta DL subframe or DL TTI that does not correspond to the intersection ofthe DL association set determined by the first processing time and theDL association set determined by the second processing time.

Alternatively, a rule may be defined such that a UE having received DLassignments (or DL grants) of different processing times that causeHARQ-ACK to be transmitted in a specific UL subframe excludes ACK/NACKfeedback information for DL data corresponding to an element of a DLassociation set determined by a shorter processing time and/or configureHARQ-ACK feedback including ACK/NACK feedback information about DL datacorresponding to an element of a DL association set determined by alonger processing time.

It is apparent that the examples of the proposed schemes may beconsidered as proposed methods since they can be included in one of themethods for implementing the present invention. The described schemesmay be implemented independently or in a combination thereof. A rule maybe defined such that the eNB deliver, to the UE, information aboutwhether the proposed methods are applied (or information on the rules ofthe proposed methods) are pre-announced to the UE by the eNB through apredefined signal (e.g., a physical layer signal or a higher layersignal).

FIG. 11 illustrates operation according to an embodiment of the presentinvention.

FIG. 11 illustrates a method for transmitting a hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) in a wireless communication system.The method may be performed by a UE, and the UE may be configured tohave two or more processing times. The UE may receive a downlink controlchannel indicating a downlink data channel and the downlink data channelfrom the base station in one or more downlink subframes (S1110). The UEmay transmit, to the base station, HARQ-ACK information about thedownlink data channel in an uplink subframe corresponding to the onemore downlink subframes (S1120). The HARQ-ACK information transmitted inthe uplink subframe may include HARQ-ACK information about a downlinkdata channel according to only one processing time of the two or moreprocessing times, and may not include HARQ-ACK information about adownlink data channel according to the other processing times.

The minimum interval between the uplink subframe and the one or moredownlink subframes corresponding to the uplink subframe may be three orfewer subframes.

When the number of the one or more downlink subframes corresponding tothe uplink subframe is greater than or equal to a certain value, theHARQ-ACK information about the downlink data channel may be bundled.Additionally or alternatively, when the number of the downlink subframescorresponding to the one uplink subframe is greater than or equal to thecertain value, the HARQ-ACK information about the downlink data channelmay be transmitted through a specific physical uplink control channel(PUCCH) format.

An information set indicating one or more downlink subframescorresponding to the uplink subframe may be configured for eachprocessing time. Here, the information set may be determined accordingto HARQ-ACK load balancing or latency priority.

FIG. 12 is a block diagram of a transmitting device 10 and a receivingdevice 20 configured to implement exemplary embodiments of the presentinvention. Referring to FIG. 12, the transmitting device 10 and thereceiving device 20 respectively include transmitter/receiver 13 and 23for transmitting and receiving radio signals carrying information, data,signals, and/or messages, memories 12 and 22 for storing informationrelated to communication in a wireless communication system, andprocessors 11 and 21 connected operationally to the transmitter/receiver13 and 23 and the memories 12 and 22 and configured to control thememories 12 and 22 and/or the transmitter/receiver 13 and 23 so as toperform at least one of the above-described embodiments of the presentinvention.

The memories 12 and 22 may store programs for processing and control ofthe processors 11 and 21 and may temporarily storing input/outputinformation. The memories 12 and 22 may be used as buffers. Theprocessors 11 and 21 control the overall operation of various modules inthe transmitting device 10 or the receiving device 20. The processors 11and 21 may perform various control functions to implement the presentinvention. The processors 11 and 21 may be controllers,microcontrollers, microprocessors, or microcomputers. The processors 11and 21 may be implemented by hardware, firmware, software, or acombination thereof. In a hardware configuration, Application SpecificIntegrated Circuits (ASICs), Digital Signal Processors (DSPs), DigitalSignal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), orField Programmable Gate Arrays (FPGAs) may be included in the processors11 and 21. If the present invention is implemented using firmware orsoftware, firmware or software may be configured to include modules,procedures, functions, etc. performing the functions or operations ofthe present invention. Firmware or software configured to perform thepresent invention may be included in the processors 11 and 21 or storedin the memories 12 and 22 so as to be driven by the processors 11 and21.

The processor 11 of the transmitting device 10 is scheduled from theprocessor 11 or a scheduler connected to the processor 11 and codes andmodulates signals and/or data to be transmitted to the outside. Thecoded and modulated signals and/or data are transmitted to thetransmitter/receiver 13. For example, the processor 11 converts a datastream to be transmitted into K layers through demultiplexing, channelcoding, scrambling and modulation. The coded data stream is alsoreferred to as a codeword and is equivalent to a transport block whichis a data block provided by a MAC layer. One transport block (TB) iscoded into one codeword and each codeword is transmitted to thereceiving device in the form of one or more layers. For frequencyup-conversion, the transmitter/receiver 13 may include an oscillator.The transmitter/receiver 13 may include Nt (where Nt is a positiveinteger) transmit antennas.

A signal processing process of the receiving device 20 is the reverse ofthe signal processing process of the transmitting device 10. Under thecontrol of the processor 21, the transmitter/receiver 23 of thereceiving device 10 receives RF signals transmitted by the transmittingdevice 10. The transmitter/receiver 23 may include Nr receive antennasand frequency down-converts each signal received through receiveantennas into a baseband signal. The transmitter/receiver 23 may includean oscillator for frequency down-conversion. The processor 21 decodesand demodulates the radio signals received through the receive antennasand restores data that the transmitting device 10 wishes to transmit.

The transmitter/receiver 13 and 23 include one or more antennas. Anantenna performs a function of transmitting signals processed by thetransmitter/receiver 13 and 23 to the exterior or receiving radiosignals from the exterior to transfer the radio signals to thetransmitter/receiver 13 and 23. The antenna may also be called anantenna port. Each antenna may correspond to one physical antenna or maybe configured by a combination of more than one physical antennaelement. A signal transmitted through each antenna cannot be decomposedby the receiving device 20. A reference signal (RS) transmitted throughan antenna defines the corresponding antenna viewed from the receivingdevice 20 and enables the receiving device 20 to perform channelestimation for the antenna, irrespective of whether a channel is asingle RF channel from one physical antenna or a composite channel froma plurality of physical antenna elements including the antenna. That is,an antenna is defined such that a channel transmitting a symbol on theantenna may be derived from the channel transmitting another symbol onthe same antenna. An transmitter/receiver supporting a MIMO function oftransmitting and receiving data using a plurality of antennas may beconnected to two or more antennas.

In embodiments of the present invention, the UE or the terminal operatesas the transmitting device 10 on uplink, and operates as the receivingdevice 20 on downlink. In embodiments of the present invention, the eNBor the base station operates as the receiving device 20 on uplink, andoperates as the transmitting device 10 on downlink.

The transmitting device and/or the receiving device may be configured asa combination of one or more embodiments of the present invention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope of the inventions. Thus, it is intendedthat the present invention covers the modifications and variations ofthis invention provided they come within the scope of the appendedclaims and their equivalents.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wireless communication devicessuch as a terminal, a relay, and a base station.

1-15. (canceled)
 16. A method for transmitting hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) by a terminal in a wirelesscommunication system, the method comprising: receiving, from a basestation, a physical downlink control channel (PDCCH) signal and aphysical downlink shared channel (PDSCH) signal scheduled by the PDCCHsignal; and transmitting, to the base station, HARQ-ACK informationabout the PDSCH signal in an uplink subframe, wherein the terminal isconfigured with a second processing time in addition to a firstprocessing time, and the second processing time is shorter than thefirst processing time, and wherein the uplink subframe for transmittingthe HARQ-ACK information is determined based on whether the PDSCH signalis related to the first processing time or the second processing time.17. The method according to claim 16, wherein when the PDSCH signal isrelated to the first processing time, the uplink subframe is determinedbased on a first downlink association set, and wherein when the PDSCHsignal is related to the second processing time, the uplink subframe isdetermined based on a second downlink association set.
 18. The methodaccording to claim 17, wherein the terminal determines physical uplinkcontrol channel (PUCCH) resources in the uplink subframe based on afirst PUCCH resource set for the first processing time or a second PUCCHresource set for the second processing time, and wherein when a downlinksubframe in which the PDSCH signal is received belongs to both of thefirst downlink association set and the second downlink association set,the PUCCH resources in the uplink subframe are determined based on thefirst PUCCH resource set, even when the PDSCH signal is related to thesecond processing time.
 19. The method according to claim 16, whereinthe HARQ-ACK information transmitted in the uplink subframe is relatedto only one of the first processing time and the second processing time.20. The method according to claim 16, wherein a minimum interval betweenthe uplink subframe and a downlink subframe in which the PDSCH signal isreceived is three subframes.
 21. The method according to claim 16,wherein, when a number of downlink subframes in a corresponding downlinkassociation set for the uplink subframe is greater than or equal to apredetermined value, HARQ-ACK information for the corresponding downlinkassociation set is bundled.
 22. The method according to claim 16,wherein, when a number of downlink subframes in a corresponding downlinkassociation set for the uplink subframe is greater than or equal to apredetermined value, HARQ-ACK information for the corresponding downlinkassociation set is transmitted in a specific PUCCH format.
 23. Aterminal configured to transmit hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) in a wireless communication system,the terminal comprising: a transmitter and a receiver; and a processorconfigured to control the transmitter and the receiver, the processorconfigured to: receive, via the receiver from a base station, a physicaldownlink control channel (PDCCH) signal and a physical downlink sharedchannel (PDSCH) signal scheduled by the PDCCH signal; and transmit, viathe transmitter to the base station, HARQ-ACK information about thePDSCH signal in an uplink subframe, and wherein the processor isconfigured with a second processing time in addition to a firstprocessing time, and the second processing time is shorter than thefirst processing time, and wherein the uplink subframe for transmittingthe HARQ-ACK information is determined based on whether the PDSCH signalis related to the first processing time or the second processing time.24. The terminal according to claim 23, wherein when the PDSCH signal isrelated to the first processing time, the uplink subframe is determinedbased on a first downlink association set, and wherein when the PDSCHsignal is related to the second processing time, the uplink subframe isdetermined based on a second downlink association set.
 25. The terminalaccording to claim 24, wherein the processor determines physical uplinkcontrol channel (PUCCH) resources in the uplink subframe based on afirst PUCCH resource set for the first processing time or a second PUCCHresource set for the second processing time, and wherein when a downlinksubframe in which the PDSCH signal is received belongs to both of thefirst downlink association set and the second downlink association set,the PUCCH resources in the uplink subframe are determined based on thefirst PUCCH resource set, even if the PDSCH signal is related to thesecond processing time.
 26. The terminal according to claim 23, whereinthe HARQ-ACK information transmitted in the uplink subframe is relatedto only one of the first processing time or the second processing time.27. The terminal according to claim 23, wherein a minimum intervalbetween the uplink subframe and a downlink subframe in which the PDSCHsignal is received is three subframes.
 28. The terminal according toclaim 23, wherein, when a number of downlink subframes in acorresponding downlink association set for the uplink subframe isgreater than or equal to a predetermined value, HARQ-ACK information forthe corresponding downlink association set is bundled.
 29. The terminalaccording to claim 23, wherein, when a number of downlink subframes in acorresponding downlink association set for the uplink subframe isgreater than or equal to a predetermined value, HARQ-ACK information forthe corresponding downlink association set is transmitted in a specificPUCCH format.